Tuesday, December 16, 2008
Parachute Jump Operations
The risks go beyond just jumping out of an airplane
In its review of the 32 accidents since 1980, the NTSB found that eight of the airplanes weren’t airworthy at the time they were dispatched. In nearly all of the accidents, the pilots held commercial or ATP certificates, yet didn’t perform adequate preflight inspections, do proper weight-and-balance calculations, maintain airspeed or properly execute emergency procedures—a fact the NTSB characterized as a “disturbing common denominator.” Twelve of the airplanes were loaded beyond their max allowable gross weights; nine of those were loaded outside of center-of-gravity limits. Twelve accidents involved loss of engine power, and nearly all of the pilots allowed the plane to stall.
On September 10, 1995, a Beech 65 crashed into a house about 2.5 miles from the municipal airport in West Point, Va. The ATP-rated pilot, 10 parachutists and a resident of the house were killed. The accident occurred in day VFR conditions.
Witnesses heard unusual engine sounds during takeoff. One person heard the engine stop for about four seconds, then regain power during takeoff. Black smoke trailed the airplane, and the witness saw it enter a shallow right turn that gradually increased to 70 to 80 degrees. The airplane then rolled into a left bank with a nose-down attitude of 45 degrees.
Investigators found that in 1975, the airplane crashed in Minnesota and was reported as destroyed; it was sold for salvage for $1 in June 1976. In November 1976, the airplane was again registered with the FAA. In 1995, the airplane was sold to the skydiving club that owned it at the time of the accident. Maintenance records didn’t indicate when the cabin seats were removed to accommodate parachutists. An FAA Form 337 had been filed indicating that floor-mounted seat belts were installed in 1990. The aircraft’s weight and balance had been recalculated, and logbook records were updated, but no such figures were found in the logbooks. More modifications were reported in 1995 via FAA 337s, but logbook entries didn’t match what was reported.
The airplane’s aft boarding door had been removed for sport parachute operations. Some Beech 65 airplanes were approved for flight with the cabin door removed, but not this one. The NTSB reported that the operator produced a “Flight Manual Supplement” stating that such door removal was authorized. The NTSB, however, reported that the document had been altered, and there were no records to indicate that the airplane had been flight-tested and authorized for flight with the door removed.
Teardown examination of the engines and propellers failed to find preexisting conditions that may have led to the accident. The airplane was found to have been about 170 pounds over gross weight, with the center of gravity about three inches aft of the limit. The NTSB’s report quoted from the FAA’s Flight Training Handbook: “Generally speaking, an airplane becomes less controllable, especially at slow flight speeds, as the center of gravity is moved aft. An airplane that cleanly recovers from a prolonged spin with the center of gravity at one position may fail completely to respond to normal recovery attempts when the center of gravity is moved aft by one or two inches.”
The probable cause of this accident was determined to be the pilot’s inadequate preflight/preparation, his failure to ensure proper weight and balance of the airplane, and his failure to obtain/maintain minimum control speed, which resulted in a loss of aircraft control after a loss of power in the right engine. The reason for the loss of power couldn’t be determined.
On June 21, 2003, a Cessna 182H was conducting an airdrop of parachutists near Cushing, Okla. A commercial pilot and five skydivers were on board, and day VFR conditions prevailed. Witnesses saw the airplane take off, circle while climbing to altitude and fly over the landing area, at which point the first parachutist jumped. The plane then made a left turn and “seemed to hang in the air,” according to a witness. The nose dropped, and the airplane started down. Two more parachutists then jumped out. When the airplane was about 300 to 400 feet AGL, a witness heard the engine power increase, but saw the airplane continue in a spin until impact. The pilot was fatally injured, two parachutists received serious injuries, two received minor injuries and one escaped injury.
Marks made in the ground and wreckage indicated that the airplane impacted in a flat attitude. There was no evidence of preimpact problems in the engine. The NTSB determined that the probable cause of this accident was the pilot’s failure to maintain airspeed, which resulted in an inadvertent stall/spin.
Peter Katz is editor and publisher of NTSB Reporter, an independent monthly update on aircraft accident investigations and other NTSB news. To subscribe, write to: NTSB Reporter, Subscription Dept., P.O. Box 831, White Plains, NY 10602-0831.
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